Compact hologram displays & method of making compact hologram

Abstract

A compact, self-contained monolith hologram display apparatus includes a laser diode mounted on an edge of a solid glass plate having a front surface with a hologram mounted thereon. The beam is expanded within the glass plate and is reflected off an opposing mirrored contoured edge surface that collimates the beam and directs it onto an angled reflection grating. The reflection grating is mounted onto an edge which is canted with respect to the front surface. The reflected beam diffracts from the grating and impinges upon the hologram to provide for reconstructed image that has achromatic properties.

The embodiments of the invention in which an exclusive property or privilege as claimed are defined as follows: 
     
       1. A hologram display apparatus characterized by: a transparent plate with a pair of opposing surfaces and edge surfaces therebetween;   one of said opposing surfaces having a hologram thereagainst;   an illuminating light source for producing a light beam for illuminating said hologram: and   said illuminating light source being optically mounted on one of said edge surfaces of said transparent plate such that expansion of said light beam from said source occurs within said transparent plate, and said illuminating light source further directing said light beam to reflect against at least one surface of said transparent plate before illuminating said hologram at said one of said opposing surface.   
     
     
       2. A hologram display apparatus as defined in claim 1, further characterized by: said at least one surface being a reflective edge surface;   said reflective edge surface having optical collimating means for collimating a diverging light beam from said illuminating light source.   
     
     
       3. A hologram display apparatus as defined in claim 2 further characterized by: said reflective edge surface opposing said first edge surface having a reflective coating thereon;   said opposing reflective edge surface being contoured and angled to collimate and direct a light beam to said one of said opposing surfaces.   
     
     
       4. A hologram display apparatus as defined in claim 2 further characterized by: a reflection grating on another of said edge surfaces to receive said collimated beam from said reflective edge surface to reflect said collimated beam onto said hologram on said one of said opposing surfaces for achromaticity of said hologram approximately at a predetermined wavelength of light.   
     
     
       5. A hologram display apparatus as defined in claim 4 further characterized by: said reflection grating being canted with respect to said one of said opposing surfaces.   
     
     
       6. A hologram display apparatus as defined in claim 1, further characterized by: said illuminating light source being a diode laser.   
     
     
       7. A hologram display apparatus as defined in claim 6 further characterized by: said at least one surface being reflective and contoured to collimate a diverging light beam from said diode laser.   
     
     
       8. A hologram as defined in claim 7 further characterized by: said at least one surface being one of said edge surfaces.   
     
     
       9. A hologram display apparatus as defined in claim 6 further characterized by: said at least one surface having a holographic diffraction reflection grating to collimate a diverging light beam from said diode laser.   
     
     
       10. A hologram as defined in claim 9 further characterized by: said at least one surface being one of said edge surfaces.   
     
     
       11. A hologram display apparatus as defined in claim 6 further characterized by: said diode laser being mounted directly on said one of the edge surfaces.   
     
     
       12. A hologram display apparatus as defined in claim 1 further characterized by: said light beam directed to internally reflect off said rear surface and to reflect off a reflective opposing edge surface that opposes said one of said edge surfaces.   
     
     
       13. A hologram display apparatus as defined in claim 12 further characterized by: said light beam being reflected from said reflective opposing edge surface and directed to said first edge surface to which said light source is optically mounted, said one of said edge surfaces having a reflective coating thereon with a window to let in said light beam from said light source.   
     
     
       14. A hologram display apparatus characterized by: a substantially planar transparent plate having first and second major surfaces that are parallel to each other, and side edge surfaces between said first and second major surfaces, said side edge surfaces including a canted side edge surface neither parallel nor perpendicular to either said first or second major surface;   a substantially planar hologram disposed on said first major surface of said transparent plate;   a substantially planar diffraction grating disposed on said canted side edge surface of said transparent plate;   said hologram having a carrier frequency and said diffraction grating having a different frequency selected with regard to a predetermined wavelength of light for causing light diffracted by said diffraction grating and by said hologram to be achromatized about said predetermined wavelength of light.   
     
     
       15. A hologram display apparatus as defined in claim 14 further characterized by: said diffraction grating being a reflective diffraction grating.   
     
     
       16. A hologram display device as defined in claim 15 further characterized by: a light collimator being mounted on a side edge of said transparent plate opposing said canted side edge surface with said reflective diffraction grating.   
     
     
       17. A hologram display apparatus characterized by: a solid transparent unit having first and second distinct and spaced surfaces;   a hologram mounted on said first surface of said solid transparent unit;   a reflective diffraction grating being mounted on said second surface of said solid transparent unit, said second surface of said solid transparent unit disposed at an angle with respect to said first surface of said solid transparent unit whereby said reflective diffraction grating receives a reconstructing light beam that passes by said hologram and substantially parallel thereto to reflect and diffract said light beam so that it impinges onto said hologram; and   said hologram diffracts said light beam from said reflective diffraction grating such that the final direction of said light beam near a predetermined center wavelength is independent of the wavelength of said beam.   
     
     
       18. A hologram display apparatus characterized by: a solid transparent member with first and second opposing surfaces and edge surfaces therebetween;   a hologram on the first of said opposing surface of said plate;   a substantially monochromatic light source for producing a reconstructive light beam for illuminating said hologram;   said monochromatic light source optically mounted on one of said edge surfaces of said member such that expansion of said light beam from said light source occurs within said member with said dispersion being substantially greater along an axis parallel with said first opposing surface and less along an axis perpendicular to said first opposing surface;   a second of said edge surfaces of said plate opposing said one of said edge surfaces and having a reflective light collimator thereon to reflect and collimate said dispersing light beam from said one of said edge surfaces and directing the collimated beam of light behind and substantially parallel to said first opposing surface;   a third of said edge surfaces adjacent to and canted at an angle with respect to said first opposing surface and said one of said edge surfaces;   said third of said edge surfaces having a reflective grating to reflect said collimated beam and direct it to impinge on said hologram; and   said reflective grating having a frequency different from the carrier frequency of the hologram and angled with respect to the hologram such that achromaticity about a predetermined wavelength of light from said light source is provided.   
     
     
       19. A hologram display apparatus as defined in claim 18 further characterized by: said substantially monochromatic light source being a laser diode.   
     
     
       20. A hologram display apparatus as defined in claim 19 further characterized by: said laser diode being mounted directly on said first edge surface.   
     
     
       21. A method of recording a hologram comprising; placing a recording medium sensitive to electromagnetic energy adjacent a front surface of a transparent body having said front surface, a rear surface, and edge surfaces therebetween;   forming a first and second beam from a coherent source of electromagnetic energy;   expanding said first beam;   creating an object wavefront by illuminating an object to be holographically recorded with said expanded first beam;   directing a portion of said object wavefront to impinge on said recording medium;   creating a reference wavefront by directing and focusing said second beam approximately at one of said edge surfaces;   diverging said second beam within said transparent body;   reflecting said expanded second beam off of one of said surfaces of said transparent body to form said reference wavefront; and   directing said reference wavefront to impinge on said recording medium and creating an electromagnetic interference pattern with said object wavefront;   rendering said interference pattern permanent in said recording medium.   
     
     
       22. A hologram display apparatus comprising: a transparent member having a substantially uniform index of refraction therein;   a hologram disposed on a first surface of said transparent member;   a reflective diffraction grating disposed on a second surface of said transparent member;   a light source for illuminating said hologram with a reconstructive light beam that expands within said transparent member, reflects and diffracts from said reflective diffraction grating to impinge on said hologram to form a holographic image.   
     
     
       23. A hologram display as defined in claim 22 further characterized by: said transparent member having a reflective surface for reflecting said reconstruction beam therein.   
     
     
       24. A hologram display apparatus as defined in claim 22 further characterized by: said light source being mounted to said transparent member.